Scientists have long known that humans remember faces of their own race more easily than faces of other races¿perhaps, as one popular theory holds, because people tend to have more experience with same-race faces. Now research described in the August issue of the journal Nature Neuroscience is shedding light on the brain activity underlying that phenomenon. The study is one of the first to probe the neural systems related to social interactions.

To examine how the brain responds to race, Jennifer L. Eberhardt of Stanford University and her colleagues showed African Americans and European Americans photographs of faces from different races, while recording their brain activity with functional magnetic resonance imaging (fMRI). Focusing on the so-called fusiform face area (FFA), a brain region thought to be important for face recognition, the team found that the FFA was more active when the subjects were looking at faces from their own racial group.

Exactly why this race-recognition bias exists remains unclear. But "regardless of whether the effect presented in the present study derives from greater perceptual expertise with same-race faces or from modulation of the FFA by other processes," the authors write, "our results demonstrate that social factors can influence this initial perception of faces and people."